Apparatus for building a carcass structure of a tyre for vehicle wheels

ABSTRACT

A process for manufacturing tyres for vehicle wheels, comprising the step of building on a forming support a carcass structure comprising at least one carcass ply and, at at least one end edge of the carcass ply, at least one annular anchoring structure comprising at least one substantially circumferential annular insert and at least one filling insert associated to said at least one substantially circumferential annular insert. The step of building the carcass structure comprises the steps of positioning the annular anchoring structure on the carcass ply by moving the annular substantially circumferential insert into contact with an end edge of the carcass ply by means of a special positioning member, pulling down the filling insert on the end edge of the carcass ply and turning up a free end portion of the end edge of the carcass ply so as to form a turned up end portion of the carcass ply including said annular anchoring structure. The pulling down of the filling insert on the end edge of the carcass ply is carried out by a special pulling down member while the substantially circumferential annular insert is retained into a contact position with the end edge of the carcass ply by said positioning member.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 12/743,135, filedMay 14, 2010, which is a national phase application based onPCT/IB2007/003500, filed Nov. 15, 2007, the content of each applicationbeing incorporated herein by reference.

BACKGROUND Field of the Invention

The present invention relates to a process for manufacturing tyres forvehicle wheels.

The invention further relates to an apparatus for building a carcassstructure of a tyre for vehicle wheels, said apparatus being usable incarrying out the above process.

Description of the Related Art

A tyre for a vehicle wheel generally comprises a carcass structurecomprising at least one carcass ply comprised of reinforcing cordsembedded in an elastomeric matrix. The carcass ply has end edgesrespectively engaged with annular anchoring structures. The latter arearranged in the zones of the tyre usually identified with the name of“beads” and normally consist each of an annular substantiallycircumferential insert on which at least one filling insert is applied,in a radially outer position thereof. Such annular anchoring structuresare commonly identified as “bead cores” and have the task of keeping thetyre well fixed to the anchoring seat specifically provided in the wheelrim, thus preventing, in operation, the radially inner end edge of thetyre coming out from such seat.

At the beads specific reinforcing structures may be provided having thefunction of improving the torque transmission to the tyre.

In a radially outer position with respect to the carcass ply, a beltstructure comprising one or more belt layers is associated, said beltlayers being arranged one on top of the other and having textile ormetal reinforcing cords with crossed orientation and/or substantiallyparallel to the direction of circumferential extension of the tyre.

Between the carcass structure and the belt structure a layer ofelastomeric material, known as “under-belt,” can be provided, said layerhaving the function of making the radially outer surface of the carcassstructure as uniform as possible for the subsequent application of thebelt structure.

In a radially outer position with respect to the belt structure a treadband is applied, made from elastomeric material as well.

Between the tread band and the belt structure a so-called “under-layer”of elastomeric material can be arranged, said layer having propertiessuitable to ensure a steady union of the tread band itself.

On the side surfaces of the carcass structure respective sidewalls ofelastomeric material are also applied, each one extending from one ofthe side edges of the tread band up to the respective annular anchoringstructure to the beads.

With particular reference to the zone of the tyre identified as “bead,”this is defined by a free end portion of the carcass ply specificallyturned up and housing the annular anchoring structure or bead core andthe filling insert therein. The coupling of the bead core to the carcassply comprises in particular for a step prior to the step of turning upthe free end portion of the carcass ply, wherein the filling insert ofthe bead core is brought into contact with the end edge of the carcassply and a step simultaneous to the step of turning up the free endportion of the carcass ply, wherein the filling insert of the bead coreis laid down or pulled down on the end edge of the carcass ply.

U.S. Pat. No. 4,508,586 describes a process wherein turning up of thefree end portion of the carcass ply and simultaneous pulling down of thefilling insert of the bead core on the end edge of the carcass ply iscarried out using an air tube specifically provided in an axially outerposition with respect to the forming support on which the carcass ply isarranged. Such air tube, once inflated, raises the free end portion ofthe carcass ply so that this can be then turned up by the effect of thethrust action exerted on the inflated air tube by a special thrustmember.

US 2005/0150587 A1 describes a process similar to the one discussedabove, wherein a specifically designed and shaped air tube is used forturning up the free end portion of the carcass ply and simultaneouslypulling down of the filling insert of the bead core on the end edge ofthe carcass ply, without the need of using any thrust member.

US 2006/0102272 A1 describes a process of the type discussedhereinabove, wherein in order to carry out the turning up of the freeend portion of the carcass ply and the simultaneous pulling down of thefilling insert of the bead core on the end edge of the carcass ply, amechanical arm provided with pressing rolls at a free end thereof isused in place of an air tube.

SUMMARY

The Applicant has noted that in the processes described above whereinthe pulling down of the filling insert on the end edge of the carcassply is carried out simultaneously to the turning up of the free endportion of the carcass ply, the keeping into position of the bead coreon the end edge of the carcass ply during the turning up of the free endportion of the carcass ply is only due to the stickiness of the rubbermixture with the rubber mixture of the fabric by which the carcass plyis made. Such stickiness is not always sufficient to ensure keeping thedesired concentricity between bead core and forming support of thecarcass structure when, during the pulling down of the filling insert,the bead core is subjected to non-negligible stresses.

The Applicant has further noted that the above stresses are especiallyhigh when assembling high performance tyres of the lowered type, whereinparticularly low and/or stocky filling inserts are used. This is due tothe high structural stiffness of such filling inserts, that is, to thehigh resistance that such inserts offer to the deformation thereof. Insuch circumstances, the traditional processes described above do notalways ensure a suitable pulling down of the filling inserts. Inparticular, the filling insert may not adhere to the carcass ply evenly,thus creating undesired air channels between filling insert and carcassply that reduce the tyre performance in use.

The Applicant has now found that it is possible to ensure keeping thedesired concentricity between bead core and forming support in theturning up of the free end portion of the carcass ply, in addition to asuitable pulling down of the filling inserts also in the case ofparticularly low and/or stocky filling inserts, by carrying out the stepof pulling down the filling insert while a special bead core positioningmember retains the bead core in contact position with the end edge ofthe carcass ply, before carrying out the turning up of the free endportion of the carcass ply.

Therefore, in a first aspect thereof, the present invention relates to aprocess for manufacturing a tyre for vehicle wheels, comprising the stepof building on a forming support a carcass structure comprising at leastone carcass ply and, at at least one end edge of said at least onecarcass ply, at least one annular anchoring structure comprising atleast one substantially circumferential annular insert and at least onefilling insert associated to said at least one substantiallycircumferential annular insert, wherein the step of assembling saidcarcass structure comprises the steps of:

-   -   positioning said at least one annular anchoring structure on        said at least one carcass ply moving said at least one        substantially circumferential annular insert in contact with        said at least one end edge of said at least one carcass ply;    -   pulling down said at least one filling insert on said at least        one end edge of said at least one carcass ply;    -   turning up a free end portion of said at least one end edge of        said at least one carcass ply so as to form a turned up end        portion of said at least one carcass ply including said at least        one annular anchoring structure; wherein the step of pulling        down said at least one filling insert on said at least one end        edge of said at least one carcass ply is carried out while said        at least one substantially circumferential annular insert is        retained into a contact position with said at least one end edge        of said at least one carcass ply by at least one positioning        member.

Advantageously, the process of the present invention allowsmanufacturing high efficiency tyres, even of the high performancelowered type, wherein the bead core position is that desired and definedin the design stage, such position not being altered by the effect ofthe stresses the bead core is subjected to during the steps of pullingdown the filling insert and turning up the free end portion of thecarcass ply. In fact, in accordance with the present invention, thesubstantial irremovability of the bead core during the pulling down ofthe filling insert is ensured by the fact that such pulling down takesplace while the bead core is held into a contact position with the endedge of the carcass ply by special bead core positioning members. Thesubstantial irremovability of the bead core during the turning up of thefree end portion of the carcass ply, on the other hand, is ensured bythe fact that the bead core adheres to the carcass ply thanks to thestickiness with the rubber mixture of the fabric by which the carcassply is made, both of the rubber mixture of the bead core and of therubber mixture of the filling insert. According to the present inventionit is therefore possible to ensure the desired concentricity betweenbead core and forming support during the pulling down of the fillinginsert and the turning up of the free end portion of the carcass ply,even in the case where particularly low and/or stocky filling insertsare used, such as those used in the assembly of high performance tyresof the lowered type.

In a second aspect thereof, the present invention relates to anapparatus for building a carcass structure of a tyre for vehicle wheelson a forming support, said carcass structure comprising at least onecarcass ply and, at at least one end edge of said at least one carcassply, at least one annular anchoring structure comprising at least onesubstantially circumferential annular insert and at least one fillinginsert associated to said at least one substantially circumferentialannular insert, said apparatus comprising:

-   -   at least one positioning member of said at least one annular        anchoring structure on said at least one end edge of said at        least one carcass ply;    -   at least one pulling down member of said at least one filling        insert on said at least one end edge of said at least one        carcass ply;    -   at least one forming member of a turned up end portion of said        at least one carcass ply;    -   wherein said at least one pulling down member is adapted to act        onto said at least one filling insert while said at least one        positioning member retains said at least one substantially        circumferential annular insert into a contact position with said        at least one end edge of said at least one carcass ply.

Advantageously, such apparatus allows carrying out the process of thepresent invention and thus, achieving the advantages mentioned above.

Throughout the present description and in the following claims, theterms “radial” and “axial” and the expressions “radially inner/outer”and “axially inner/outer” are used with reference to the radialdirection and to the axial direction of the forming support.

The present invention, in at least one of the aforementioned aspectsthereof, can have at least one of the following preferred features.

In the preferred embodiments of the present invention, the pulling downof the filling insert is carried out by pushing the filling insertagainst the forming support while the substantially circumferentialannular insert is retained by thrust against said forming support bysaid at least one positioning member. Advantageously, in this way theundesired movement of the annular anchoring structure with respect tothe forming support during the pulling down of the filling insert andthe subsequent turning up of the free end portion of the carcass ply isprevented.

According to a first embodiment of the present invention, the pullingdown of the filling insert is carried out by exerting a predeterminedthrust on at least a portion of a side surface of said at least onefilling insert by at least one thrust member.

Preferably, the side surface portion of the filling insert whereon thethrust is initially exerted is a radially outer portion and the step ofpushing the filling insert comprises the step of axially moving theabove thrust member for exerting said thrust on a progressively largerportion of the side surface of the filling insert starting from saidradially outer portion along the whole radial extension of said sidesurface.

Advantageously, an effective adhesion of the filling insert on thecarcass ply is thus obtained, with clear advantages in terms of tyrequality and performance.

In a particularly preferred embodiment of the present invention, saidthrust member has a predetermined profile.

Preferably, such predetermined profile is a profile conjugated to thatof the side surface of the filling insert when the filling insert ispulled down on the end edge of the carcass ply. Advantageously, such anarrangement allows obtaining, in a very short time, a substantially evenpulling down of the filling insert on the carcass ply.

According to a second embodiment of the present invention, the sidesurface portion of the filling insert on which the thrust is initiallyexerted is a radially inner portion and the step of pushing the fillinginsert comprises the step of axially moving said thrust member forexerting said thrust on a different portion of the side surface of thefilling insert starting from said radially inner portion to continue ona radially outer portion of the side surface with respect to saidradially inner portion.

Advantageously, such solution is especially advantageous since it allowscarrying out the same process and using the same apparatus as the sizeof the filling insert and the fitting change.

Preferably, said thrust is exerted by a plurality of pressing membersarranged adjacent to one another along a circumferential direction andhaving a predetermined profile.

In preferred embodiments of the present invention, said pressing memberscomprise rollers having a concave profile. Preferably, such concaveprofile has as bending radius greater than 3 mm compared to the radiusof the forming support, and more preferably smaller than 5 mm comparedto the radius of the forming support.

In specific embodiments of the present invention, the filling insert hasa height not greater than 30 mm, preferably not greater than 25 mm.

In further specific embodiments of the present invention, the fillinginsert has a height not lower than 7 mm.

Preferably, the filling insert has a height comprised between 7 and 30mm, more preferably between 7 and 25 mm.

Preferably, the filling insert has a substantially triangular shape,with a base having a length shorter than 12 mm.

In the preferred embodiments of the apparatus of the present invention,the pulling down member of the filling insert is mechanically associatedto the positioning member of the annular anchoring structure and ismechanically separate from the forming member of the turned up endportion of the carcass ply. In this way it is possible to carry out thepulling down while the positioning member is operating in retaining theannular anchoring structure into position on the end edge of the carcassply and before actuating the forming member.

Preferably, the pulling down member of the filling insert is slidinglyassociated to the positioning member of the annular anchoring structure.Advantageously, the pulling down of the filling insert therefore iscarried out by the effect of the stroke of the pulling down member withrespect to the positioning member of the annular anchoring structurewhile the latter is operating in retaining the annular anchoringstructure into position on the end edge of the carcass ply.

Preferably, the stroke of the pulling down member of the filling insertis controlled by a hydraulic cylinder, or by any other conventionaldevice that in any case ensures a thrust on the pulling down membersufficient for the deformation of the filling insert.

Preferably, the pulling down member of the filling insert is removablyassociated to the positioning member of the annular anchoring structure,so as to be removed for any maintenance and/or replacement operations.Such device further allows providing a plurality of pulling down membersdifferent from one another by dimensions and profile of the surfaceintended to come into contact with the filling insert, so as to fit themost suitable pulling down member on the apparatus according to thedimensions and the profile of the filling insert to be pulled down.

As already mentioned, in a first preferred embodiment of the presentinvention, the pulling down member of the filling insert comprises athrust member of the filling insert against the forming support.

In a first preferred embodiment of the present invention, said thrustmember has a predetermined profile, preferably a profile conjugated tothat of the side surface of the filling insert when the filling insertis pulled down on the end edge of the carcass ply.

In a second preferred embodiment of the present invention, the pullingdown member of the filling insert comprises at least one pressing membermechanically associated to the thrust member of the filling insert.

Preferably, said pressing member comprises a respective arm pivoted tothe thrust member at a pivoting axis substantially perpendicular to aradial plane of the forming support and a respective roller rotatablyassociated to said arm, the arm further being elastically associated tothe thrust member for keeping the contact with the filling insert duringthe pulling down of the filling insert.

More preferably, the pressing member comprises a traction springoperatively arranged between said arm and said thrust member. Of course,it is possible to provide elastic means other than the traction springto carry out the same function.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will appearmore clearly from the following detailed description of some preferredembodiments of an apparatus and process according to the presentinvention, made with reference to the annexed drawings. In suchdrawings:

FIG. 1 is a schematic partly cutaway view of a longitudinal section of aportion of a first embodiment of an apparatus that carries out a processaccording to the present invention, such apparatus being in a firstoperating configuration thereof;

FIG. 2 is a schematic view of the apparatus of FIG. 1 in a secondoperating configuration thereof;

FIG. 3 is a schematic partly cutaway view of a longitudinal section of aportion of a second embodiment of an apparatus that carries out aprocess according to the present invention, such apparatus being in afirst operating configuration thereof;

FIG. 4 is a schematic view of the apparatus of FIG. 3 in a secondoperating configuration thereof;

FIG. 5 is a schematic view of the apparatus of FIG. 3 in a thirdoperating configuration thereof;

FIG. 6 is a schematic side view of a portion of the apparatus of FIG. 3;

FIG. 7 is a schematic view showing a step of the process of the presentinvention following that illustrated in FIGS. 2 and 5.

DETAILED DESCRIPTION

In FIGS. 1 and 2, reference numeral 100 globally indicates a firstillustrative embodiment of an apparatus usable in a process formanufacturing a tyre for vehicle wheels, according to a first embodimentof the present invention. In particular, apparatus 100 is used in a stepof building a carcass structure of the tyre for arranging one or moreannular anchoring structures 10 (hereinafter also called bead cores) atthat region of the carcass structure that will constitute the bead ofthe tyre. Such annular anchoring structures 10 are intended to keep thetyre well fixed to the anchoring seat specifically provided in the rimof the vehicle wheel.

The building of the carcass structure of the tyre comprises thepreliminary step of arranging a carcass ply 2 on a substantiallycylindrical forming support 50 and after that, the step of associatingeach annular anchoring structure 10 to an end edge 2 a of the carcassply 2.

In the embodiment illustrated in FIGS. 1-2, the annular anchoringstructure 10 is associated to the end edge 2 a of the carcass ply 2 at aside shoulder 51 of the forming support 50, such forming support 50being rotatably mounted about an axis of rotation X-X in a totallyconventional manner.

The structure of the forming support 50 is not described in detailherein as it can be made in any convenient manner by a man skilled inthe art.

As illustrated in FIGS. 1 and 2, each annular reinforcing structure 10comprises at least one substantially circumferential annular insert 11on which at least one filling insert 12 is applied in a radially outerposition thereof.

Always with reference to FIGS. 1 and 2, apparatus 100 comprises a member110 sliding parallel to the axis of rotation X-X of the forming support50, and thus in the two opposite ways of the direction indicated inFIGS. 1 and 2 by arrow F, so as to move close to, or away from, theforming support 50. The movement of ring 110 towards, and away from, theforming support 50 is carried out in a totally conventional manner bymeans known by a man skilled in the art.

Ring 110 is intended to bring the annular anchoring structure 10 incontact with the end edge 2 a of the carcass ply 2. In particular, asillustrated in FIGS. 1 and 2, ring 110 acts on the substantiallycircumferential annular insert 11 of the annular anchoring structure 10pushing it against shoulder 51 of the forming support 50, thuspositioning the annular anchoring structure 10 in the desired positionon the end edge 2 a of the carcass ply 2. Throughout the presentdescription, ring 110 shall also be defined as “bead core holder ring”.

The bead core holder ring 110 comprises a tubular portion 111 extendingparallel to the axis of rotation X-X of the forming support 50 and anannular portion 112 extending perpendicular to the aforementioned axisof rotation X-X. Sliding guides 113 extending parallel to the axis ofrotation X-X of the forming support 50 are provided on the radiallyouter annular surface of the tubular portion 111 of the bead core holderring 110.

According to the present invention, apparatus 100 of FIGS. 1 and 2comprises a member 120 slidingly mounted, by special guides 123, on thesliding guides 113 of the bead core holder ring 110.

In the specific embodiment illustrated in FIGS. 1 and 2, member 120 ismade in the shape of a ring 121, but it is possible to envisagedifferent embodiments, such as for example a plurality of membersarranged side by side in circumferential direction so as tosubstantially define a ring.

Ring 121 is intended to slide with respect to the bead core holder ring110 in the direction indicated in FIG. 1 by arrow G for pushing thefilling insert 12 of the annular anchoring structure 10 against shoulder51 of the forming support 50, thus obtaining the pulling down of thefilling insert 12 on the end edge 2 a of the carcass ply 2,substantially as illustrated in FIG. 2. Throughout the presentdescription, ring 121 shall be defined as “filling insert pulling downring.”

In the specific embodiment illustrated in FIGS. 1 and 2, the movement ofthe filling insert pulling down ring 121 is controlled by a piston 131of a hydraulic cylinder 130 suitably arranged in the proximity of theforming support 50, for example on a support bracket 61 of a supportframe 60. Piston 131 is rigidly associated to the filling insert pullingdown ring 121 and crosses a hole—62 formed on a side wall 63 of thesupport frame 60 and a hole 115 formed on the annular portion 112 of thebead core holder ring 110 and axially aligned to hole 62.

Of course, in place of the hydraulic cylinder 130 any other conventionaldevice may be used which in any case guarantees a thrust sufficient fordeforming the filling insert 12 of the annular anchoring structure 10.

As illustrated in FIG. 2, the filling insert pulling down ring 121 actson the filling insert 12 of the annular anchoring structure 10 while thebead core holder ring 110 pushes the substantially circumferentialannular insert 11 of the annular anchoring structure 10 against theshoulder 51 of the forming support 50.

Preferably, the filling insert pulling down ring 121 is removablyassociated to the bead core holder ring 110 so as to be removed for anymaintenance and/or replacement operations.

The filling insert pulling down ring 121 preferably has a side surface125 having a predetermined profile. More preferably, the profile of theside surface 125 is conjugated to that of the corresponding side surface12 a of the filling insert 12 when such insert is pulled down on the endedge 2 a of the carcass ply 2, so as to act on the entire annular andradial extension of the side surface 12 a during the pulling down of thefilling insert 12.

With reference to FIGS. 1 and 2, a preferred embodiment of the processthat can be carried out by apparatus 100 described above shall now bedescribed.

In a first process step, illustrated in FIG. 1, the annular anchoringstructure 10 is pushed by the bead core holder ring 110 against theshoulder 51 of the forming support 50. In particular, the bead coreholder ring 110 acts by thrust on the substantially circumferentialannular insert 11 up to bring it in contact with the end edge 2 a of thecarcass ply 2 previously positioned on the forming support 50. Theradial position of the substantially circumferential annular insert 12on the end edge 2 a of the carcass ply is predetermined in the designstage.

In this step, the end portion 2 b of the end edge 2 a is kept shiftedtowards the axis of rotation X-X of the forming support 50 by specialmembers (not shown), so as to allow the bead core holder ring 110 tocome close to the forming support 50. Moreover, in this step, thefilling insert pulling down ring 121 is kept into a position axiallyspaced from the filling insert 12.

In a subsequent step, illustrated in FIG. 2, while the bead core holderring 110 continues to act by thrust on the substantially circumferentialannular insert 11 for retaining it into position against shoulder 51 ofthe forming support 50, the filling insert pulling down ring 120 isaxially pushed by the hydraulic cylinder 130, by means of the piston 131thereof, against shoulder 51 of the forming support 50. In this step,the pulling down of the filling insert 12 on the end edge 2 a of thecarcass ply 2 is carried out.

In particular, such pulling down takes place by first exerting apredetermined thrust on a radially outer portion of the side surface 12a of the filling insert 12 and then, by axially moving the thrust ring121 towards the forming support 50, exerting such thrust on aprogressively larger portion of the side surface 12 a of the fillinginsert 12 starting from the aforementioned radially outer portion alongall the radial extension of the side surface 12 a.

The aforementioned step allows the steady anchoring of the annularanchoring structure 10 on the end edge 2 a of the carcass ply 2. Suchsteady anchoring is ensured by the stickiness with the rubber mixture ofthe carcass ply 2 both of the rubber mixture of the substantiallycircumferential annular insert 11 of the annular anchoring structure 10and of the rubber mixture of the pull down filling insert 12.

FIGS. 3 to 5 show in a sequence the operating steps of an alternativeembodiment of the apparatus of the present invention, globally indicatedwith reference numeral 200. In such embodiment, elements identical tothose described before with reference to apparatus 100 of FIGS. 1 and 2are indicated with the same reference numeral.

Apparatus 200 of FIG. 3-5 differs from apparatus 100 of FIG. 1-2 only inthat the pulling down of the filling insert 12 on the end edge 2 a ofthe carcass ply 2 takes place by a member 220 of a different type fromthe filling insert pulling down ring 120 used in apparatus 100 of FIGS.1 and 2. Apart from this, apparatus 200 is totally identical toapparatus 100 of FIGS. 1 and 2.

In particular, in apparatus 200 of FIG. 3 the filling insert pullingdown member 220 comprises a thrust ring 221 slidingly associated to thebead core holder ring 110 in a manner totally similar to the fillinginsert pulling down ring 121 of apparatus 100 of FIGS. 1 and 2, and aplurality of pressing members 222 (only one of which being illustratedin FIGS. 3-5) arranged side by side in a circumferential direction (FIG.6) and each elastically associated to the thrust ring 221.

In particular, each pressing member 222 comprises a respective arm 223pivoted on the thrust ring 221 at a special pin 224 having a pivotingaxis substantially perpendicular to a radial plane of the formingsupport 50.

Arm 223 is further elastically associated to the thrust ring 221 by atraction spring 225 active along a predetermined direction defined inthe above radial plane for keeping arm 223 pressed against portion 111of the bead core holder ring 110. In substance, arm 223, when stressedin a direction opposite that wherein the elastic return stress exertedby spring 225 acts, is movable in clockwise direction around pin 224 inthe radial plane of the forming support 50.

Each pressing member 222 further comprises a roller 226 rotatablyassociated to the respective arm 223. Roller 226 preferably has aconcave profile, with a bending radius greater than 3 mm, and morepreferably smaller than 5 mm, compared to the radius of the formingsupport 50.

Preferably, the coupling between rollers 226 and arms 223 and thatbetween arms 223 and thrust ring 221 is of removable type.

The process carried out by apparatus 200 of FIG. 3-5 is totally similarto that carried out by apparatus 100 of FIG. 1-2 described above, withthe only difference that, as shown in the sequence of FIGS. 3 to 5, thepulling down of the filling insert 12 on the end edge 2 a of the carcassply 2 in this case takes place by the effect of the rolling of rollers226 on the side surface 12 a of the filling insert 12 starting from aradially inner portion of such side surface 12 a to continue on aradially outer portion of the side surface 12 a with respect to theaforementioned radially inner portion. Such rolling takes place by theeffect of the axial movement of the thrust ring 221 which, actuated bythe hydraulic cylinder 130 by means of piston 131, is pushed againstshoulder 51 of the forming support 50. During their rolling, rollers 226are kept pressed on the filling insert 12 by the elastic return actionexerted by spring 225.

Also in this case, as shown in particular in FIGS. 4 and 5, rollers 226act on the filling insert 12 of the annular anchoring structure 10 whilethe bead core holder ring 110 pushes the substantially circumferentialannular insert 11 of the annular anchoring structure 10 against shoulder51 of the forming support 50.

In the building step of the carcass structure of the tyre, theaforementioned steps of positioning the annular anchoring structure 10on the end edge 2 a of the carcass ply 2 and of pulling down the fillinginsert 12 are repeated several times if more than one annular anchoringstructure 10 must be associated to the end edge 2 a of the carcass ply2.

Moreover, further operating steps may be provided besides thosedescribed above, wherein specific reinforcing structures (not shown) areassociated to the carcass ply 2 in radially and/or axially outer and/orinner position with respect to each annular anchoring structure 10.

Both in the case in which apparatus 100 of FIG. 1-2 or apparatus 200 ofFIG. 3-5 is used, subsequent to the step of pulling down the fillinginsert 12 and optionally to the step of laying the above, reinforcingstructures, an operating step is provided wherein the end edge 2 a ofthe carcass ply 2 is turned up on itself so as to form a turned up endportion 20 of the carcass ply 2 comprising the annular anchoringstructure 10 and optionally the above reinforcing structures (FIG. 7)therein.

Such step can be carried out in a conventional manner, for example bythe use of an air tube 140 of the conventional type and of a shaped ring150, also of the conventional type, movable in a direction E parallel tothe axis of rotation X-X of the forming support 50 (FIG. 7). Inparticular, the air tube 140, once inflated, lifts a free end portion 2b of the end edge 2 a of the carcass ply 2. At that point, the shapedring 150 pushes such air tube 140 towards shoulder 51 of the formingsupport 50 thus forming the turned up end portion 20 of the carcass ply2 and thus, the tyre bead.

According to the present invention, therefore, the member 140 thatcarries out the turning up of the end portion of the carcass ply 2 isoperatively separate from member 120, 220 that carries out the pullingdown of the filling insert 12 of the annular anchoring structure 10.

A step of passing a pressing member (not shown) on the turned up end 20of the carcass ply 2 is also preferably provided in order to compact thetyre bead.

The use of apparatus 100 and 200 of the present invention isparticularly advantageous when the filling insert to be pulled down isparticularly low and stocky, with a height not greater than 30 mm, morepreferably not greater than 25 mm, and even more preferably not smallerthan 7 mm.

Preferably, moreover, the filling insert has a substantially triangularshape, with a base having a length shorter than 12 mm.

Of course, what said above also applies when filling inserts havingdifferent height and shape than those mentioned above are used.

From the above description it is clear that the various embodiments ofthe process and of the apparatus described above allow manufacturinghigh efficiency tyres, even of the high performance lowered type,wherein the bead core position is the one desired and defined in thedesign stage, such position not being altered by the effect of thestresses the bead core is subjected to during the steps of pulling downthe filling insert and turning up the free end portion of the carcassply. This occurs thanks to the fact that the step of pulling down thefilling insert is carried out before the turning up step and inparticular, while the bead core is retained into a contact position withthe end edge of the carcass ply by a special bead core positioningmember.

1-24. (canceled)
 25. An apparatus for building a carcass structure of atyre for a vehicle wheel on a forming support, the carcass structurecomprising a carcass ply, and, at an end edge of the carcass ply, anannular anchoring structure comprising a substantially circumferentialannular insert and a filling insert associated with the substantiallycircumferential annular insert, comprising: a positioning member of theat least one annular anchoring structure on the at least one end edge ofthe at least one carcass ply; a ring having a side surface with apredetermined profile, wherein the predetermined profile of the sidesurface of the ring is conjugated to a profile of a side surface of thefilling insert when pulled down on the end edge of the carcass ply toact on the entire side surface of the filling insert annularly andradially; and a forming member of a turned up end portion of the atleast one carcass ply, wherein the at least one pulling down member isadapted to act on the at least one filling insert while the at least onepositioning member retains the at least one annular substantiallycircumferential insert in a contact position with the at least one endedge of the at least one carcass ply.
 26. The apparatus according toclaim 25, wherein the ring is controlled by a hydraulic cylinder with apiston.
 27. The apparatus according to claim 26, wherein the ringaxially pushes the filling insert onto the edge of the carcass ply bythe piston of the hydraulic cylinder.
 28. The apparatus according toclaim 27, wherein the turning-up member comprises an air tube to lift afree end portion of the end edge.
 29. The apparatus according to claim28, wherein the ring is removably associated with the positioningmember.
 30. The apparatus according to claim 29, wherein the fillinginsert has a height not greater than 30 mm.
 31. The apparatus accordingto claim 30, wherein the filling insert has a height not lower than 7mm.
 32. The apparatus according to claim 31, wherein the filling inserthas a substantially triangular shape, with a base having a lengthshorter than 12 mm.
 33. The apparatus of claim 32, wherein the ringexerts a thrust action initially on a radially outer annular portion ofthe side surface of the filling insert and then on progressively largerportions of the side surface of the filling insert starting from theradially outer portion along the whole radial extension of the sidesurface of the filling insert.
 34. The apparatus of claim 33, whereinthe positioning member comprises a tubular portion extending parallel toan axis of rotation of the forming support and having, on a radiallyouter annular surface thereof, sliding guides extending parallel to theaxis of rotation, and wherein the ring is slidingly mounted on thesliding guide and slides with respect to the tubular portion of thepositioning member.